1. Field of the Invention
This invention relates to automatic clothes washing machines, and more particularly to a method and apparatus for minimizing the "setting" in of wrinkles in fabrics during a liquid extraction cycle.
2. Description of the Prior Art
The usual method for extracting moisture from clothes in an automatic washer is to centrifuge the clothes load at a high speed to force out the water. With permanent press fabrics, however, difficulties arise in that the centrifuging process may result in the fabrics becoming pressed causing the introduction of wrinkles. In some cases, the wrinkles become "set" into the fabric and cannot be entirely removed in a subsequent drying process, whether that process involves the use of a dryer or hanging the clothes on a clothes line. A drying machine normally does a better job of removing wrinkles from synthetic fabrics than can be achieved by hanging the fabrics to dry on a clothes line since the heat from the dryer tends to "relax" the fabrics; however, if the wrinkles are sufficiently "set" into the fabric during the centrifuging operation in the washer, they may not be removed, even when the fabrics are dried in a clothes dryer.
As will be noted below, the "setting" of wrinkles in permanent press fabrics may be lessened by reducing the spin speed of the washer, but for normal fabrics a high spin speed is desirable to efficiently centrifuge moisture therefrom.
One technique for overcoming the aforementioned "setting" in of wrinkles problem is to provide a multi-speed motor, usually a two-speed motor, so that a spin speed may be utilized during a permanent press cycle, without sacrificing effectiveness or efficiency in other washer performance areas. The provision of a multi-speed motor is, however, a disadvantage in that such motors are substantially more expensive than single speed motors.
Another possible solution to the problem of setting in wrinkles is to limit the duration of a high speed spin so that excessive moisture removal will not occur. This approach is generally not feasible due to mechanical limitations in the timer mechanism of the machine, and would also be undesirable due to the possibility that regular fabrics could remain excessively wet at the end of the machine cycle where permanent press and normal fabrics were combined in a single load.
Techniques for adding liquid to fabrics being dried in a clothes dryer are well known in the art. For example, D. L. Clark in his U.S. Pat. No. 2,846,776 teaches the introduction of a liquid spray to the interior of a dryer drum through the utilization of compressed air.
P. W. Douglas U.S. Pat. No. 3,570,272 discloses the use of a liquid spray of long duration during a spin cycle of an automatic washer in order to obtain a more efficient suds removal and N. S. McEwen U.S. Pat. No. 2,915,890 discloses the provision of a liquid spray in a clothes washer for rinsing.
A. U. Khan et al, in their U.S. Pat. No. 3,116,243, assigned to Whirlpool Corporation, disclose the provision of a liquid spray from outside a perforate drum as an aid in removing clothes adhering to the wall of the drum.
In U.S. Pat. No. 3,526,105, T. B. Anthony teaches the use of a low speed spin as a means of gently extracting moisture from permanent press fabrics.